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# pcc - simple pascal-like compiler based on LLVM
## How to build
### linux & macOS & FreeBSD
- download the LLVM 10.0.0 prebuilt binary at [LLVM release page](https://releases.llvm.org/download.html#10.0.0)
- extract the tarball
- make a build directory under the source directory
- run `cmake .. -DCMAKE_BUILD_TYPE=Release -DCMAKE_PREFIX_PATH=/path/to/the/llvm/`
- run `cmake --build . -j8`
### windows
- get the awesome package manager [vcpkg](https://github.com/Microsoft/vcpkg)
- run .\vcpkg.exe install llvm:x64-windows
- make a build directory under the source directory
- run `cmake .. -DCMAKE_TOOLCHIAN_FILE=/path/to/your/vcpkg/toolchain/file`
- run `cmake --build . -j8`
### How to run
```
Usage: pcc [-vVhiScad] [-O <0,1,2,3>] [-o <output>] file...
-v Verbose mode.
-vv Very verbose mode.
-V Show version and exit.
-h Show this help and exit.
-i Generate LLVM IR (default behavior).
-S Compile to assembly file.
-c Compile to object file.
-o <output> Specify output file name.
-O <0,1,2,3> Specify optimization level.
-a Dump the AST.
-d Generate a dot file for AST.
```
You can find some examples at the t directory.
#### compile pascal file to executable
```
./pcc -c qsort.pas
```
Then you need to link the object file qsort.o by your host-compiler.
- gcc case: `gcc -no-pie qsort.o`
- clang case: `clang qsort.o`
- msvc case: find the developer command window, use cl to link
#### calling C functions from pascal
See ssl.pas and extern.pas.
For the `scanf` case, the `scanf` may be a marco in C like `__isoc99_scanf`, so you may need to wrap the scanf function, see common.pas.
#### calling pascal functions from C
See sha1.pas and sha1_driver.pas.
### How to get the tree or graph view of AST
pass -a to pcc, you will get a tree view of AST like this:
```
`-FunctionNode FunctionName=main ReturnType=integer
|-VarDeclNode local size=2
| |-Variable name=arr type=integer[100000]
| `-Variable name=i type=integer
`-StatementListNode size=5
|-FunctionCallNode FunctionName=srand ResultType=void
| `-FunctionCallNode FunctionName=time ResultType=integer
| `-IntegerLiteralNode value=0
|-ForStatementNode direction=up
| |-IdentifierNode lvalue name=i type=^integer
| |-IntegerLiteralNode value=0
| |-IntegerLiteralNode value=99999
| `-AssignStatementNode ValueType=int64
| |-ArrayAccessNode ResultType=^integer
| | |-IdentifierNode lvalue name=arr type=^integer[100000]
| | `-L2RCastingNode ResultType=integer
| | `-IdentifierNode lvalue name=i type=^integer
| `-BinaryExprNode op='%' ResultType=int64
| |-FunctionCallNode FunctionName=rand ResultType=integer
| `-IntegerLiteralNode value=1000
|-FunctionCallNode FunctionName=qsort ResultType=void
| |-IdentifierNode lvalue name=arr type=^integer[100000]
| |-IntegerLiteralNode value=0
| `-IntegerLiteralNode value=99999
|-ForStatementNode direction=down
| |-IdentifierNode lvalue name=i type=^integer
| |-IntegerLiteralNode value=99999
| |-IntegerLiteralNode value=0
| `-FunctionCallNode FunctionName=printf ResultType=integer
| |-StringLiteralNode value='%d \x00'
| `-L2RCastingNode ResultType=integer
| `-ArrayAccessNode ResultType=^integer
| |-IdentifierNode lvalue name=arr type=^integer[100000]
| `-L2RCastingNode ResultType=integer
| `-IdentifierNode lvalue name=i type=^integer
`-AssignStatementNode ValueType=int64
|-IdentifierNode lvalue name=main type=^integer
`-IntegerLiteralNode value=0
```
pass -d to pcc, it will generate a dot file, use graphviz to render it.
```
pcc -d qsort.pas
dot -Tpng -o qsort.png qsort.dot
```
|
